An example of a centrifugal separator is referred to in WO 90/04460. In that centrifugal separator, the inlet chamber is shielded from separating chamber by a dividing wall in the form of seal means which are disposed in recesses in the separating discs or are integrated with the respective separating discs if the separating discs and the seal means are made of plastic. In addition to having to cater to a large number of separating discs, the seal means disposed in recesses in the separating discs entail problems in catering to many more parts which will, if the seal means are for example made of a rubber material, be liable to wear and have to be replaced at regular intervals. Seal means integrated with the respective separating discs and made of plastic involve limitations with regard to the strength of the separating discs. The material characteristics of the discs and seals also limit the applications for which the centrifugal separator can be used.
A common way of holding rotor parts of the kind indicated above together is to cause them to be in engagement with one another by means of threaded connections as referred to in WO 90/04460. The separating discs are held securely in place by rods and are compressed by a compression tool to increase the rigidity of the fitted separating discs. Compression of the separating discs presses them together so much as to affect their symmetry and mutual positioning, thus possibly causing imbalance which might be critical when the rotor rotates.